1. Field of the Invention
The present invention relates to a machine for manufacturing a material web, in particular a paper or cardboard web, comprising a drying section comprising heatable drying cylinders wherein the material web is guided between and to successive drying cylinders.
2. Discussion of Background Information
Machines of for manufacturing a material web are known, and are disclosed, for example, in EP 0 479 748 B1. They comprise a drying section exhibiting a drying group with two rows. The drying group encompasses several drying cylinders arranged in an upper row and a bottom row, around which a material web is guided together with a transport belt. The material web is guided in a free stretch in the area between the drying cylinders, i.e. the material web is not supported by a transport belt in this area or zone. A known machine furthermore comprises of a nozzle device, serving to transfer a threading strip (also simply called a strip) providing a gas flow which runs against the run direction of the material web.
In the event of a web tear, or during the initiation of operation of the machine for manufacturing a material web, the threading strip is first cut out of the material web leaving a press section and then threaded through the drying section. This usually occurs at full operating speed of the material web manufacturing machine. It is therefore required that the threading strip be guided and stabilized, so that on the one hand it does not wrap around one of the drying cylinders, and on the other hand can be transferred safely in the transfer area between the upper and bottom row of drying cylinders. In the known machine, a nozzle device is used for this purpose and is located in the area of the opening nip of a drying cylinder, i.e. in the spool-off area, and which receives the material web from the drying cylinder, so that it can be transferred--viewed in the run direction of the material web--to the subsequent drying cylinder of the other row. It was demonstrated as a disadvantage that the transfer of the threading strip did not always occur safely, thereby often interrupting the threading process and requiring the cleaning of the drying section, which can result in machine down-time.